Purification of the human NF-E2 complex: cDNA cloning of the hematopoietic cell-specific subunit and evidence for an associated partner.

The human globin locus control region-binding protein, NF-E2, was purified by DNA affinity chromatography. Its tissue-specific component, p45 NF-E2, was cloned by use of a low-stringency library screen with murine p45 NF-E2 cDNA (N. C. Andrews, H. Erdjument-Bromage, M. B. Davidson, P. Tempst, and S. H. Orkin, Nature [London] 362:722-728, 1993). The human p45 NF-E2 gene was localized to chromosome 12q13 by fluorescent in situ hybridization. Human p45 NF-E2 and murine p45 NF-E2 are highly homologous basic region-leucine zipper (bZIP) proteins with identical DNA-binding domains. Immunoprecipitation experiments demonstrated that p45 NF-E2 is associated in vivo with an 18-kDa protein (p18). Because bZIP proteins bind DNA as dimers, we infer that native NF-E2 must be a heterodimer of 45- and 18-kDa subunits. Although AP-1 and CREB copurified with NF-E2, no evidence was found for heterodimer formation between p45 NF-E2 and proteins other than p18. Thus, p18 appears to be the sole specific partner of p45 NF-E2 in erythroid cells. Cloning of human p45 NF-E2 should permit studies of the role of NF-E2 in globin gene regulation and erythroid differentiation.     

Cytogenetic mapping of eight genes encoding fatty acid binding proteins (FABPs) in the pig genome

In the present study cytogenetic localization of eight fatty acid binding protein genes in the pig genome was shown. BAC clones, containing sequences of selected genes (FABP1, FABP2, FABP3, FABP4, FABP5, FABP6, FABP7 and FABP8) were derived from porcine BAC libraries and mapped by FISH to porcine chromosomes (SSC) 3q12, 8q25, 6q26, 4q12, 4q12, 16q22, 1p22 and 4q12, respectively. Detailed analyses of regions containing gene clusters (FABP4, FABP5, FABP8) in chromosome 4 were performed and their order was established. It was shown that these three genes are located beyond the FAT1 region. Assignment of the FABP genes to chromosome regions harboring quantitative trait loci (QTL) for fat deposition is discussed.     

MetaHox gene clusters

Homeobox genes encode important developmental control proteins. The Drosophila fruit fly HOM complex genes are clustered in region 84-89 of chromosome 3. Probably due to large-scale genome duplication events, their human HOX orthologs belong to four paralogous regions. A series of 13 other homeobox genes are also clustered in region 88-94, on the same chromosome of Drosophila. We suggest that they also duplicated during vertebrate evolution and belong to paralogous regions in humans. These regions are on chromosome arms 4p, 5q, 10q, and 2p or 8p. We coined the term "paralogon" to designate paralogous regions in general. We propose to call these genes "meta Hox" genes. Like Hox genes, metaHox genes are present in one cluster in Drosophila and four clusters (metaHox A-D) in humans on the 4p/5q/10q paralogon.